AxiSEM: broadband 3-D seismic wavefields in axisymmetric media

Nissen‐Meyer, Tarje; Driel, Martin van; Stähler, Simon C.; Hosseini, Kasra; Hempel, S.; Auer, L. M.; Colombi, Andrea; Fournier, Alexandre

doi:10.5194/se-5-425-2014

Cited by 239 publications

(166 citation statements)

References 68 publications

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“…As it is based on the weak formulation of the wave equation, it naturally includes the free surface boundary condition and allows for highly accurate modeling of surface waves. Nissen-Meyer et al (2014) argued against using collective parallel I/O since the availability of the NetCDF libraries (Rew and Davis, 1990) was not granted on all supercomputers. For that reason, we implemented a round robin I/O scheme, which remains advantageous when running AxiSEM on less than about 100 cores in parallel and to avoid installation problems on systems where NetCDF is not available as a pre-compiled package.…”

Section: Computing Green's Functions With Axisemmentioning

confidence: 99%

Instaseis: instant global seismograms based on a broadband waveform database

et al. 2015

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Abstract. We present a new method and implementation (Instaseis) to store global Green's functions in a database which allows for near-instantaneous (on the order of milliseconds) extraction of arbitrary seismograms. Using the axisymmetric spectral element method (AxiSEM), the generation of these databases, based on reciprocity of the Green's functions, is very efficient and is approximately half as expensive as a single AxiSEM forward run. Thus, this enables the computation of full databases at half the cost of the computation of seismograms for a single source in the previous scheme and allows to compute databases at the highest frequencies globally observed. By storing the basis coefficients of the numerical scheme (Lagrange polynomials), the Green's functions are 4th order accurate in space and the spatial discretization respects discontinuities in the velocity model exactly. Highorder temporal interpolation using Lanczos resampling allows to retrieve seismograms at any sampling rate. AxiSEM is easily adaptable to arbitrary spherically symmetric models of Earth as well as other planets. In this paper, we present the basic rationale and details of the method as well as benchmarks and illustrate a variety of applications. The code is open source and available with extensive documentation at www.instaseis.net.

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Section: Computing Green's Functions With Axisemmentioning

confidence: 99%

Instaseis: instant global seismograms based on a broadband waveform database

et al. 2015

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“…Also, AxiSEM since then has experienced some substantial development (Nissen-Meyer et al 2014), specifically the improved parallelization allows us to perform production runs up to the highest frequencies observed for global body waves. Fig.…”

Section: High Frequency Seismogramsmentioning

confidence: 99%

“…The numerical implementation (AxiSEM) was recently published under GNU general public license (www.axisem.info) and a whole variety of applications is presented by Nissen-Meyer et al (2014). Stähler et al (2012) use this method to compute finite frequency sensitivity kernels for triplicated P waves, which is inaccurate with other methods such as the one by Dahlen et al (2000) due to the strong influence of the upper-mantle discontinuities in comparison to their sensitivity to mantle heterogeneity.…”

Section: Introductionmentioning

confidence: 99%

Seismic wave propagation in fully anisotropic axisymmetric media

Driel

Nissen‐Meyer

2014

Geophysical Journal International

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S U M M A R YWe present a numerical method to compute 3-D elastic waves in fully anisotropic axisymmetric media. This method is based on a decomposition of the wave equation into a series of uncoupled 2-D equations for which the dependence of the wavefield on the azimuth can be solved analytically. Four independent equations up to quadrupole order appear as solutions for moment-tensor sources located on the symmetry axis while single forces can be accommodated by two separate solutions up to dipole order. This decomposition gives rise to an efficient solution of the 3-D wave equation in a 2-D axisymmetric medium. First, we prove the validity of the decomposition of the wavefield in the presence of general anisotropy. Then we use it to derive the reduced 2-D equations of motions and discretize them using the spectral element method. Finally, we benchmark the numerical implementation for global wave propagation at 1 Hz and consider inner core anisotropy as an application for high-frequency wave propagation in anisotropic media at frequencies up to 2 Hz.

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“…Users only need to provide scripts that connect this metadata input to their desired computational engine (other than Syngine), for example, AxiSEM (Nissen-Meyer et al, 2014) or Instaseis (van Driel et al, 2015).…”

Section: Requesting Synthetic Seismogramsmentioning

confidence: 99%

ObspyDMT: a Python toolbox for retrieving and processing large seismological data sets

Hosseini

Sigloch

2017

Solid Earth

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Abstract. We present obspyDMT, a free, open-source software toolbox for the query, retrieval, processing and management of seismological data sets, including very large, heterogeneous and/or dynamically growing ones. ObspyDMT simplifies and speeds up user interaction with data centers, in more versatile ways than existing tools. The user is shielded from the complexities of interacting with different data centers and data exchange protocols and is provided with powerful diagnostic and plotting tools to check the retrieved data and metadata. While primarily a productivity tool for research seismologists and observatories, easy-to-use syntax and plotting functionality also make obspyDMT an effective teaching aid. Written in the Python programming language, it can be used as a stand-alone command-line tool (requiring no knowledge of Python) or can be integrated as a module with other Python codes. It facilitates data archiving, preprocessing, instrument correction and quality control -routine but nontrivial tasks that can consume much user time. We describe obspyDMT's functionality, design and technical implementation, accompanied by an overview of its use cases. As an example of a typical problem encountered in seismogram preprocessing, we show how to check for inconsistencies in response files of two example stations. We also demonstrate the fully automated request, remote computation and retrieval of synthetic seismograms from the Synthetics Engine (Syngine) web service of the Data Management Center (DMC) at the Incorporated Research Institutions for Seismology (IRIS).

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AxiSEM: broadband 3-D seismic wavefields in axisymmetric media

Cited by 239 publications

References 68 publications

Instaseis: instant global seismograms based on a broadband waveform database

Instaseis: instant global seismograms based on a broadband waveform database

Seismic wave propagation in fully anisotropic axisymmetric media

ObspyDMT: a Python toolbox for retrieving and processing large seismological data sets

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